Gene Therapy Improves Vision for Some with Rare Disease

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Two adults with a rare disease that causes gradual loss of
eyesight had their vision improved after being treated with a new
gene therapy, according to preliminary results from a new study.

The study involved six patients ages 35 to 63 with choroideremia,
an inherited condition with no cure that causes vision problems
early in life, and eventually leads to blindness. Patients have a
mutation in a gene called CHM, which causes light-sensitive cells
in the eye to slowly stop working.

The new study was an early test of the therapy in which the
researchers aimed to carry out the treatment without causing
damage to the eye. (Patients must have an eye surgery so that the
virus can be injected under the retina with a fine needle).

The result showed that the treatment did not cause harm, and in
fact, improved vision in a few of the patients.

Six months after the treatment, four patients recovered the
visual acuity (clearness or acuteness of vision) that they had
before the surgery, and developed increased sensitivity to light.
And two patients had improvements in vision: They were able to
read two to four more lines on a sight chart.

"We did not expect to see such dramatic improvements in visual
acuity," study researcher Robert MacLaren, of the Nuffield
Laboratory of Ophthalmology at the University of Oxford in the
U.K., said in a statement. It is still too early to know if the
improvements will last, but they have so far been maintained for
as long as two years, MacLaren said.